Wrapping your key fob in tin foil does work to stop car thieves from blocking out signals from the key fobs which the car thieves could hack to steal your car.
FBI security expert Holly Hubert confirms that wrapping the key fob in tin foil does work to block out the signals.
The attack the car thieves do on key fobs to steal cars is called a relay attack and the tin foil blocks out those signals so the relay attack cannot happen.